import matplotlib.pyplot as plt

f=open('arenstorf-rk.txt','r')

X = []
Y = []
T = []

for line in f:
    line = line.replace(',', '.')
    line = line.strip()
    vals = line.split(' ')
    T.append(float(vals[0]))
    X.append(float(vals[1]))
    Y.append(float(vals[2]))

plt.figure(1)
plt.ylabel('Y[1]')
plt.xlabel('Y[2]')
plt.plot(X, Y)
plt.show()
